The field of the present invention is diaphragms for fluid driven diaphragm pumps.
Air driven double diaphragm pumps employ a source of pressurized air for operation and are quite versatile in their ability to pump a wide variety of materials. Pumps having double diaphragms driven by compressed air directed through an actuator valve are found in U.S. Pat. Nos. 7,399,168; 7,063,516; 6,435,845; 6,357,723; 6,257,845; 5,957,670; 5,169,296; 4,247,264; Des. 294,946; Des. 294,947; and Des. 275,858. Actuator valves used in such pumps are illustrated in the foregoing and in U.S. Pat. Nos. 7,125,229; 6,102,363; 4,549,467. Diaphragms used in such pumps are illustrated in the foregoing pump patents and in U.S. Pat. Nos. 5,743,170; 4,270,441; 4,238,992. The disclosures of the foregoing patents and published application are incorporated herein by reference. Pressurized fluids other than air may be employed to drive these devices. If liquids are used, alternate valve arrangements would be appropriate.
Such pumps include an air chamber housing having a center section and two concave discs facing outwardly from the center section. Pump chamber housings oppose the two concave discs. The pump chamber housings are coupled with an inlet manifold and an outlet manifold through ball check valves positioned in the inlet passageways and outlet passageways from and to the inlet and outlet manifolds, respectively. Diaphragms extend outwardly to mating surfaces between the concave discs and the pump chamber housings. The diaphragms with the concave discs and with the pump chamber housings each define an air chamber and a pump chamber to either side thereof. At the centers thereof, the diaphragms are fixed to a control shaft by pump pistons. The control shaft slidably extends through the air chamber housing.
Actuator valves associated with such pumps include feedback control mechanisms. Such mechanisms typically have airways on the control shaft attached to the diaphragms and a valve piston. Pressurized air is supplied to the valve piston. This pressurized air is alternately distributed to the air chambers through the valve piston. The valve piston is controlled by control shaft or pump piston location which in turn is controlled by distribution of air through the valve piston. The resulting alternating pressurized air drives the diaphragms back and forth. In turn, the pump chambers alternately expand and contract to pump material there through. Such pumps are capable of pumping a wide variety of materials of greatly varying consistency.
The diaphragms used in such pumps have been made in a variety of shapes and constructions. Diaphragms can be molded flexible plates sandwiched between rigid external piston plates or, alternatively, integral bodies including a rigid piston integral with an annular flexure portion, among others. Molded diaphragms have been formed with a central piston and a flexible peripheral portion concave toward the air side. A rigid body forms the interior of the piston with a unitary covering including the peripheral portion molded about the rigid body in situ. The rigid body may be thermoplastic with the unitary covering being of thermoplastic elastomer thermally miscible with the thermoplastic coating. An insert, made of rigid material, is located at the hub and has a center attachment with a threaded bore accessible from one side of the diaphragm and a plurality of radially outwardly extending engagement flanges displaced from one another and embedded in the rigid body. The expected life of diaphragms used in air driven devices contemplates vast numbers of cycles, alternating pressures, tensions and flexures. Because of these expectations, the molded diaphragms have maximum utility in small sizes where robust pistons are more easily accommodated and the composite structures can better withstand the cycling under less destructive forces.